The suspension spring is placed around the rod of a damper piston the end of which, usually the end of the piston rod, is secured to the supporting block. The suspension thrust bearing device thus makes it possible to transmit axial forces between the spring and the body shell of the vehicle while allowing a relative angular movement between a bearing mount of the spring, that is able to rotate, and the supporting block that is fixed and secured to the body shell of the vehicle. This relative angular movement can arise from a steering of the steered wheel and/or from the compression of the suspension spring.
Certain suspension thrust bearing devices are fitted with shock-absorbing pads surrounding the rod of the damper cylinder and designed to be compressed between the body of the cylinder and the device when there are extreme travels of the suspension. This prevents the damper rod from bottoming in the cylinder.
Document GB 2 347 906 describes a suspension thrust bearing device comprising a bottom cover made of plastic having a radial extension extending towards the inside of the suspension spring and serving as a bearing surface for the shock-absorbing pad. Such a bottom cover lacks rigidity during impacts generated by extreme travels of the suspension.
Document FR 2 857 906 describes suspension thrust bearing device comprising a rolling bearing mounted on a bottom cover. The bottom cover described comprises a body made of synthetic material and a reinforcing metal insert covered by said cover. The metal insert gives the bottom cover a good mechanical strength to the axial forces generated by the compression of the shock-absorbing pad. Moreover, the metal insert is embedded into the body made of synthetic material. This makes it possible to use a raw steel insert and prevents having recourse to corrosion-prevention treatments of the insert. Moreover, the bottom cover described comprises an annular rib used for centring the spring and separating the bearing surfaces of the spring and of the shock-absorbing pad. When there are impacts generated by the extreme travels of the suspension, the shock-absorbing pad is compressed axially and extends radially. It is noted however that the annular rib can be damaged by the radial expansion of the shock-absorbing pad.
Document FR 2 899 154 also describes a suspension thrust bearing device of a vehicle fitted with a shock-absorbing pad. The device comprises a bottom cover placed between the spring and the shock-absorbing pad on one side and the bearing of the device on the other. A metal cup is interposed between the bottom cover and the shock-absorbing pad. The metal cup is used for the radial confinement of the shock-absorbing pad. This cup is an additional part making assembly of the suspension more complex. Moreover, the metal cup must be treated against corrosion. Moreover, the cup described has a bore for the passage of the damper rod. Finally, when there are extreme travels of the suspension, the metal edge of the passage bore of said cup can damage the shock-absorbing pad and reduce its service life.
The invention proposes a suspension thrust bearing device designed to accommodate a shock-absorbing pad and a telescopic strut which remedy the aforementioned drawbacks.